Cranioplasty Prosthesis and Components Therefor

The present application is a continuation of U.S. patent application Ser. No. 18/704,506, which is a 371 application of PCT Application No. PCT/CA2022/051571, which claims the priority of U.S. Patent Application No. 63/271,432, filed on Oct. 25, 2021, and incorporated herein by reference.

The present application pertains to implants, attachment devices, fixation plates, plating systems, and/or prostheses used in surgical procedures such as craniotomies, craniectomies and/or cranioplasties.

Some neurosurgical procedures pertain to the temporary or permanent removal of a bone flap from a skull for various reasons. For example, a craniotomy is a procedure by which a bone flap is temporarily removed to access part of a brain, blood vessels or like soft tissue within the skull. In a craniotomy, the bone flap is replaced at the end of the procedure, before skin closure. A craniectomy is a procedure by which the bone flap is permanently removed from a remainder of the skull. This can be performed to reduce intracranial pressure (decompressive craniectomy), because the skull itself is fractured beyond repair, or infected and must be removed for the infection to heal. In a craniectomy, the skin is closed without the bone flap in place, leaving an area of the brain unprotected. A cranioplasty is the reinsertion of the bone flap or equivalent prosthesis to cover the opening in the skull.

Cranioplasty may often occur several weeks after a craniectomy, once the intracranial pressure has returned to acceptable levels or the infection has cleared. In some instances, custom-made cranial prostheses are used in cranioplasty, post-craniectomy. As it is difficult to predict the geometrical parameters of a bone flap prior to surgery, there may result an extended period in which a skull has an uncovered craniectomy opening, leaving a portion of the brain unprotected structurally at the skull. In the case of decompressive craniectomy, to allow a reduction in the intracranial pressure, there must often be a period in which the bone flap is removed.

Therefore, patients in the wait for cranioplasty may be at high risk of injury and must often be kept in a hospital or like controlled environment. As one possible occurrence, the sinking flap syndrome may occur and may involve serious complications, such as paralysis or coma. Moreover, a subsequent intervention is then required to install a cranial prosthesis or bone flap, resulting in costs and further hospitalization time.

Dynamic systems have been developed to allow bone flaps to move and expand the intracranial volume, thereby allowing a “decompressive craniotomy”. The dynamic systems may typically include telescopic or spring-based expansion. However, such systems may be voluminous and may exhibit unnecessary resistance to bone flap or prosthesis movement, thereby providing insufficient decompression. Moreover, dynamic systems voluminous in nature may be unaesthetic in that they may create lumps on one's head.

In a first aspect, there is provided an attachment device for cranioplasty comprising a body defined from a sheet material and including: a first connection end having at least a first connection hole configured to cooperate with a fastener to anchor the attachment device to a bone flap or prosthesis covering at least part of the opening in the skull, a second connection end having at least a second connection hole configured to cooperate with a fastener to anchor the attachment device to a skull adjacent to an opening in the skull, a frame portion extending from the first connection end, and a coil portion between the frame portion and the second connection end, the coil portion having struts configured for deforming in flexion, and webs between the struts configured for deforming in torsion, wherein the frame portion is configured to be located over a periphery of the opening in the skull to block inward movement, and wherein the coil portion enables an out-of-plane deformation of the attachment device for the first connection end to move out of a neutral plane with the second connection end.

Further in accordance with the first aspect, for example, the body extends lengthwise from the first connection end to the second connection end, with at least some of the struts extending at least partially lengthwise.

Still further in accordance with the first aspect, for example, at least some of the webs extending at least partially widthwise.

Still further in accordance with the first aspect, for example, the second connection end has a pair of the second connection holes.

Still further in accordance with the first aspect, for example, the coil portion has a first set of coils and a second set of coils, the first set of coils and the second set of coils connected to a respective one of the second connection holes and merging at the frame portion.

Still further in accordance with the first aspect, for example, the second connection holes form rotational joints with fasteners configured to secured the second connection end to the skull, the rotational joints enabling lengthwise expansion of the attachment device.

Still further in accordance with the first aspect, for example, a part of the coil portion is on one side of a line passing through the second connection holes, the first connection end being on the other side of the line.

Still further in accordance with the first aspect, for example, the part flares in toward the line.

Still further in accordance with the first aspect, for example, the frame portion has a closed frame between the first connection end and the coil portion.

Still further in accordance with the first aspect, for example, an entirety of the contour edges of the body is arcuate.

Still further in accordance with the first aspect, for example, the first connection end has a pair of the first connection holes.

Still further in accordance with the first aspect, for example, the frame portion has a strut extending lengthwise from the coil portion.

Still further in accordance with the first aspect, for example, the attachment device has a symmetry axis extending lengthwise.

In accordance with a second aspect, there is provided a cranioplasty prosthesis comprising: a pair of the attachment device as described above; and a prosthetic blade a body defined from a sheet material and including: a first connection end configured to be anchored to a first position of a skull by one of the attachment devices, a second connection end configured to be anchored to a second position of the skull by the other of the attachment devices, the first position and the second position being separated by a skull opening, and an elongated plate portion between the first connection end and the second connection end, the elongated plate portion having a main surface facing toward the skull opening, wherein the sheet material is a rigid biocompatible material deformable out of plane.

Further in accordance with the second aspect, for example, the body has holes.

Still further in accordance with the second aspect, for example, the body is elongated.

Still further in accordance with the second aspect, for example, the attachment devices and the prosthetic blade are a monoblock component.

In accordance with a third aspect, there is provided a prosthetic blade for covering a skull opening in cranioplasty comprising: a body defined from a sheet material and including: a first connection end configured to be anchored to a first position of a skull, a second connection end configured to be anchored to a second position of the skull, the first position and the second position being separated by the skull opening, and an elongated plate portion between the first connection end and the second connection end, the elongated plate portion having a main surface facing toward the skull opening; wherein the sheet material is a rigid biocompatible material deformable out of plane.

Further in accordance with the third aspect, for example, the body has holes.

Still further in accordance with the third aspect, for example, the body is elongated.

Referring to the drawings and more particularly to, there is illustrated a cranioplasty prosthesis in accordance with the present disclosure at. The cranioplasty prosthesisis shown spanning across an opening Sin a skull S. The opening Smay result from a craniectomy procedure, for example. For simplicity, a single cranioplasty prosthesisis shown and therefore only partially covers the opening Sin the skull S but a plurality of the cranioplasty prosthesiscould be used in a side-by-side arrangement, in a manner similar to the embodiment shown in.

The cranioplasty prosthesisis of the type that is used to temporarily or permanently cover the opening S, for instance pursuant to a cranioectomy procedure or a craniotomy procedure. The expression “cranioplasty” is used as a moniker for the prosthesisin that the prosthesisserves to cover the opening Sin the skull S. While the use of the cranioplasty prosthesisis described in a context of craniotomy, craniectomy, or cranioplasty, it may be used in other circumstances as well.

The cranioplasty prosthesisis shown as being made of a pair of attachment devicesat opposite ends of a prosthetic blade, in accordance with a variant of the present disclosure. The attachment devicesmay be deformable to allow an adjustment of the prosthetic bladerelative to the skull S, while the prosthetic bladedefines the structural component of the cranioplasty prosthesisthat acts as a temporary or permanent skull shell portion to cover the opening S. The prosthetic blademay also be made of a shapeable material, such as a metallic plate, such that the prosthetic blademay be shaped into a given curvature in continuity with the surrounding cranium surfaces, while providing suitable impact resistance to protect the brain. In the illustrated embodiment of, the attachment devicesand the prosthetic bladeare monoblock in construction. For example, the attachment devicesand the prosthetic blademay be made of a single sheet of material that may be cut in any appropriate way, such as by laser cutting, CNC machining, casting, etc. It is also possible to mechanically attach the attachment devicesto the prosthetic bladeso as to have three components, separable from one another. For example, the attachment devicesmay be secured to the prosthetic bladeby screws, by welding, by glueing, etc. The attachment devicesmay also be used as fixations for bone flaps, i.e., with the prosthetic blade.

In accordance with a variant of the present disclosure, the cranioplasty prosthesismay have a single one of the attachment device(s), i.e., only at one end of the prosthetic blade, with the prosthetic bladeanchored directly to the skull at the other end. In accordance with another variant, the prosthetic blademay be used without the attachment device, with other securement means provided to anchor the prosthetic bladeto the skull S, such as screws. Such prosthetic blademay not allow a dynamic adjustment of shape at the coverage of the opening S, for instance to address intracranial pressure concerns, but may nevertheless form a prosthetic flap that provides suitable structural integrity. Moreover, the prosthetic blademay be shaped into a given geometry to match surrounding outer cranium surfaces, while also relieving some pressure due to their thinness in comparison to bone flaps.

An enlarged view is provided into illustrate that the attachment devicemay be secured to the bone of the skull by way of screws F. Other securement means are considered as well, including bolts, suture, adhesives, etc. Referring to, it is observed that the cranioplasty prosthesishas a planar body extending in length L, relative to width W, with a thickness of the planar body being substantially thinner than the width W (e.g., at least 10 times less). The planar body may be made of a biocompatible material or of a combination of materials, such as a metal or a polymer. For example, titanium is well suited to be used to define the cranioplasty prosthesis, such as titanium in a sheet format. The material is a rigid material but may exhibit some flexibility due to its limited thickness. Therefore, the cranioplasty prosthesismay have portions deformable out of a flat plane (e.g., when the cranioplasty prosthesisis made from a sheet). The deformation may be in the elastic deformation range and may also reach plastic deformation. This may be observed inin which it is shown that the prosthetic bladeis curved, for example to match a shape of surrounding outer cranium surfaces. Due to the use of a rigid material, and the width and length substantially greater than the thickness, in-plane deformation may not be possible, i.e., deformation while the cranioplasty prosthesisremains planar. More specifically, the cranioplasty prosthesiswill not deform while remaining in the L-W plane (). The cranioplasty prosthesismay also oppose to any buckling by its configuration.

The out-of-plane deformation of the prosthetic blade, embodied inby the curve, may allow a user to manually define a shape of the prosthetic blade, for instance to emulate a geometry of the bone flap that is removed. In a variant, the shape may be obtained by applying the prosthetic bladeagainst a target site of the skull S, before craniectomy. Instruments may optionally be used to shape the blades. Measuring instruments, that may for example emulate the shape of the skull, may be used to obtain physical shape representations. Bladesof different length may be put side by side, to customize a shape of a flap constituted of numerous blades, as in. The elongated nature of the blades, whether or not part of the cranioplasty prosthesis, may facilitate their insertion in a small incision, for example with endoscopic maneuvers. A single incision, sized based on the width of a single blade, may be used for the insertion of all blades, when numerous blades are used. Moreover, the rounded ends of the blades, though optional, are without corners and hence reduce risks of catching surrounding soft tissue when the bladesare slid into position, for instance by a pushing movement on the trailing end of the bladesor of the cranioplasty prosthesis. Other tapering shapes are considered for the blades, in addition to the hemi-circular end geometry shown.

Referring to, an exemplary embodiment of the attachment deviceis provided. As explained above, the attachment devicemay or may not be part of the cranioplasty prosthesis. For example, the attachment devicemay be used alone to join a skull to a bone flap, to a prosthetic shell, or to a prosthesis differing from the prosthetic blade. The attachment deviceis designed to allow relative and constrained movement between bone flap, prosthetic shell, or prosthesis covering the opening S, and the skull surface surrounding the opening S. The movement may be described as being mostly out of plane, with a residual bi-directional movement in length L.

The attachment deviceofis shown having a planar body and may be made of a sheet material, in a monoblock construction. For example, the attachment deviceofmay be made of a single sheet of material that may be cut in any appropriate way, such as by laser cutting, CNC machining, casting, etc. For reference, the attachment devicemay, in a neutral position, lie in a plane defined by the length L and the width W. The neutral position may be a native condition of the attachment device. The plane defined by the length L and the width W may be a flat plane, but may also have a curved condition, i.e., a curved plane.

The attachment devicehas a first connection endand a second connection end. The first connection endis defined by a pair of holesA that are configured to receive a fastener such as screw F of. Fewer or more holesA may be present, or other connection members may be present, such as spikes, tacks, nails, glue, etc. Likewise, the second connection endalso has a pair of holesA (or more or fewer) to receive fasteners such as screw F of. In an embodiment, the holesA are aligned with one another along the width W. Likewise, in an embodiment, the holesA are aligned with one another along the width W. Other arrangements are considered. In a variant, the holesA and/or the holesA have the illustrated circular shape (e.g., straight hole, hole with counterbore, hole with countersink). Complementary fasteners such as screws F () or the like (pins, bolts, etc) are received in the holesA and/orA, thereby defining a rotational joint, provided that the fasteners are not too tightly installed. The rotational joints may therefore enable a rotational movement, as described below and shown by R, about rotational axes Hthat may be generally parallel to height H.

The first connection endand the second connection endare interconnected by a coil portion, for instance formed of multiple coils, and by a frame portion. The coil portionmay also be referred to as a switchback mechanism, with multiple switchbacks. In use, the attachment devicehas the first connection endsecured to the skull S adjacent to the skull opening S. The second connection endmay be connected to a bone flap or prosthesis covering the skull opening S, such as the prosthetic blade. The reverse arrangement is also possible. Therefore, while the second connection endis shown as having holes to be screwed to a component, the second connection endmay be integrally connected to the blade portionas shown in.

The coil portionis responsible for allowing out-of-plane movement of the second connection endrelative to the first connection end, withshowing the attachment device at′ after having sustained an out-of-plane deformation, relative to the attachment devicein its neutral position (also referred to herein as original condition). The coil portionis configured to constrain movement of the first connection endsuch that the first connection endis practically superposed in height H with itself in a manner shown in. The rotational joints at the endmay contribute to this quasi-superposition. Stated differently, the coil portionis arranged to limit the first connection endto movement along the height H. While the first connection endmay also move along length L, the variation in distance along length L when projected onto the neutral plane (i.e., original condition) is substantially less than the variation in distance along height H. The frame portion, on the other end, is between the first connection endand the coil portion. The frame portionis a rigid component (i.e., no in-plane deformation) that may optionally be located over the kerf, to force a unidirectional deformation characteristic of the attachment device, namely to enable movement upwardly from a neutral condition, as explained below. Thus, movement of the first connection endin the width W direction is limited or negligible, due to the physical constraints imposed by the frame portion. As can be observed, the coil portionis connected to the frame portion, and the frame portionenables various types of deformation of the coil portion, while the frame portionmay deform in flexion only, in a variant. Although the movement is described as being that of the first connection end, similar behavior may apply to the first connection endfrom the perspective of the second connection end. In use, in an embodiment, it is the second connection endthat leads when slid into an incision. Although not necessary, the flaring shape from the leading end to the trailing holesA, and the trailing position of the holesA relative to a tip of the coil portionin direction-L, limits movement in H, and contributes to maintaining the attachment deviceplanar and moving along the surface of the skull. The flaring shape from the leading end to the trailing holesA may be described as being arcuate, or may have other shapes, if present.

The coil portionand frame portionconstrain the movements of the endsandrelative to one another, by having various components. The coil portionhas strutsA that extend at least partially in the length L direction. The strutsA may be interconnected by websB. The websB may be shorter than the strutsA, and may be located at ends of the strutsA. For example, the websB may be transverse to the strutsA and may extend at least partially in the width W direction. Therefore, when one of the endsandis subjected to a force, such as that shown in, the websB deform by the leveraging effect of the strutsA, allowing the out-of-plane movement of the strutsA. The websB serves as rotational joints (along W), by deformation. Although the strutsA and websB are described as distinct features, the coil portionmay have curved sections that behave as strutsA and websB, the websB being at junctions with other strutsA to which the curved sections are connected. Again, the strutsA and websB may all be made of a single sheet material. In a variant, the websB may be said to exhibit torsion when out-of-plane movement occurs for the strutsA. In parallel to the torsion of the websB, the strutsA may exhibit flexion, in the out-of-plane movement. In a variant, any such torsion may be in elastic deformation (though it could also be in plastic deformation). When subjected to a deformation, the attachment devicemay be defined as a compliant mechanism, i.e., a flexible body that elastically deforms. Moreover, by its configuration, the attachment devicemay be said to be unidirectional in its displacement from its original condition (shown in lighter tone in), in that it may move only in one direction from the original condition (neutral plane), namely toward the deformed condition shown in. In its original condition, the attachment devicecannot move in the other direction through normal in-use forces and pressures. Stated differently, the attachment devicecannot deform in negative H from the neutral plane/original condition. This is because the frame portionof the attachment deviceis essentially transverse to and above a kerf between skull and flap, such that the attachment deviceprevents inward movement of the flap. i.e., depression of the bone flap. The frame portionis shown as having a strutA, at the first end of which the coil portionis connected. The coil portionmay be said to be divided in two sets of coils from the strutA of frame portion. In a variant, the strutA extends along L. Other arrangements are possible, with pairs of strutsA, etc. The frame portionmay further include a frame memberB at the end of which are located the connection holesA of the first connection end. Therefore, there is no coil portion, thus deformation of the frame portionis limited, in contrast to the coil portion. This can be observed in, for example.

Moreover, as observed from, the optional rotational joints at the end(with fasteners such as F ()), enable rotation of the first coil portions in direction R as the attachment devicemoves out of the neutral plane, i.e., rotation about axes H. This may be possible by the fact that the connection holesA are each connected to respective coils of the coil portion, referred to as sets above. This rotation results in an expansion of the attachment devicealong direction L, contributing to the footprint of the attachment devicein the deformed condition to be close to the footprint in the neutral condition. It can also be observed that the coil portionhas segments that are in a direction opposite the connection end, relative to line Lpassing through the connection holesA. This may result in a greater span of movement of the first connection endrelative to the second connection end.

In a variant, the second connection end, i.e., featuring the rotational joints, is on the skull, whereas the first connection end is connected to the flap or to the blade. The first connection endhas a single member interconnecting the holesA, and thus there may not be any substantial rotation at the holesA.

By the combination of the various actions, i.e., rotation, torsion, flexion, with deformations occurring in the elastic deformation range, the displacement versus force plot line may exhibit a non-linear behavior (in contrast to spring-based systems complying with Hooke's law), and thus may result in greater displacement to force ratios. This may be useful when relieving intracranial pressure. An exemplary graph is provided into illustrate this.

Referring to, another embodiment of the attachment deviceis shown, and like reference numerals represent like elements for all embodiments shown herein. The attachment devicemay include a closed frameD as part of the frame portion. The closed frameis a rigid component (i.e., no in-plane deformation) that may be optionally located over the kerf, to force the unidirectional deformation characteristic of the attachment device. The presence of a third holeA may also contribute to the rigid securing of the first connection endto a bone flap, for example. The presence of an anchor holeD at the junction of the coil portionand the frame portion, or in the frame portion, may block rotation about H, and could be present to give the attachment devicethe possibility to be used as described above, or as a fixed anchor. The frame portion(e.g., via the strutA and/or holeD) interconnects the two halves of coil portions, and thus blocks flexion, torsion, rotation. The two halves may not be similar, and may be regarded as two sets of coils, i.e., a first set of coils and a second set of coils, the first set of coils and the second set of coils connected to a respective one of the second connection holesA and merging.

Referring to, the attachment devicemay have one or more axes of symmetry, with one such axis of symmetry being substantially parallel to the length L direction. By being connected on both sides of the axis of symmetry, or otherwise on both sides of a central axis parallel to length L, the attachment deviceis generally prevented from a torsion along length L.

shows different attachment device shapes that can be used to achieve such out-of-plane deformation. All of the embodiments ofmay be made from a sheet of material with all of these figures being from a plane view. The shapes ofhave sets of strutsA and websB in their coil portions, and a frame portionthat would be positioned above a kerf. Moreover, although it is not necessary, the attachment device shapes all have a symmetry axis that is parallel to the length L direction. In all of the attachment devices of, connection features, such as holes, are on opposite sides of a central axis that is parallel to the length L direction. The central axis may be coincident with the symmetry axis.

The proposed thickness of the attachment devicecould vary between 0.4 mm and 0.6 mm, inclusively. It may be possible to make it thicker or thinner. This limited thickness is used in the interest of an appropriate aesthetic outcome. The width may be 25 mm±2 mm and the length between 20 mm and 35 mm, inclusively. These dimensions could vary depending on the dynamic displacement needed, with these dimensions being merely given as an example. The material used is for example titanium grade 23 (TiAl6V4 ELI). This material may be used for its capacity to withstand significant deformation before plastic deformation. Chosen for its malleability and the possibility of manufacturing in its sheet form, the titanium grade 23 is well suited to be used for the attachment deviceand for the prosthetic blade.

The attachment deviceis well suited to anchor a prosthesis or bone flap to the skull and allow a dynamic unidirectional movement, i.e., movement essentially limited to displacement of a connection endorin the height H direction, from a neutral plane, and possibly back toward the neutral plane. Accordingly, the attachment deviceallows displacement of a bone flap or prosthesis as a reaction to intracranial pressure. Consequently, the increase in the cerebral volume may limit damages caused by intracranial hypertension. In its neutral position, the attachment deviceoffers its maximum shearing resistance, thereby preventing an inward movement of the bone flap or prosthesis. The flaring shape from the leading end to the holesA may also contribute to the prevention of inward movement. The attachment devicemay be made of any appropriate material that is semi-flexible, biocompatible and/or biodegradable, such as metals and plastics.

The attachment devicemay be used in a hybrid manner, for instance by use as part of the cranioplasty prosthesisor to connect a bone flap to a remainder of the skull. For example, in the latter scenario, while not as optimal in addressing intracranial pressure issues as with the cranioplasty prosthesis(as the prosthetic bladeis substantially thinner than a bone flap), the presence of the attachment devicemay allow some form of decompression as well.

Referring to, the prosthetic bladeis shown as having an elongated body between its first connection endand its second connection end. The elongated body is a planar body and may also be made of a sheet material, in a monoblock in construction, that is manufactured for example using laser cutting, CNC machining, casting, etc. For reference, the prosthetic blademay, in a neutral position, lie in the plane defined by the length L and the width W. The neutral position may be a native condition of the prosthetic blade. The plane defined by the length L and the width W may be a flat plane, but may also have a curved condition, i.e., a curved plane. The main surfaces of the prosthetic blade, i.e., one having the brain in use and one oriented away from the skull, extend in the length L and width W directions. A thickness of the prosthetic blademay be substantially less than the length and width of the main surfaces, whereby the prosthetic blademay be deformable out of plane from its native condition, in the elastic and optionally plastic deformation range.

So as not to damage surrounding tissue, the first connection endand the second connection endmay be rounded or have like arched shapes, though other shapes are also possible. In the illustrated embodiments, the overall shape of the prosthetic blademay be described as obround. As shown in, the prosthetic blademay have the attachment devicesintegral therewith, or may have the attachment devicesmechanically connected thereto, such as with fasteners. As observed in the variant of, holesA andA may be defined in the first connection endand the second connection end, respectively, for the prosthetic bladeto be anchored directly to the skull by a fastener (e.g., screw F of), or to the attachment deviceor other attachment means. The prosthetic blademay be used alone, for instance in scenarios in which no expansion is required to counter any increase in intracranial pressure.

A plurality of holesmay be defined in a main surface of the prosthetic bladeso as to lessen the weight of the prosthetic blade, increase its flexibility and/or allow a scanning through the prosthetic blade, for instance if a radiopaque material is used for the prosthetic blade. The holesmay also serve for the attachment of devices to the blades, such as fillers, monitoring devices or sensors, drains, etc. As observed in, various lengths and widths of prosthetic bladesare possible. Therefore, during surgery, an operator may have access to a plurality of blades of different sizes, as shown in, in order to have customized coverage of the opening S, with the bladesbeing used in the side-by-side arrangement shown, though other patterns are possible, with overlap, for example. In, it is observed that the prosthetic bladesdo not extend onto the skull S, and this implies that attachment devicesor equivalents may be used. However, the prosthetic bladescould extend to overlap a surface of the skull S for the bladesto be secured directly to the skull S.